A remnant oak-savannah ecosystem, rich in native plant species and also heavily invaded by exotics.

An abandoned 19th century barn is located within a remnant oak-savannah ecosystem in southwestern British Columbia, Canada. The herbaceous vegetation in the foreground includes the pink-flowered native plant Henderson’s shooting star (Dodecatheon hendersonii) growing among dense populations of invasive grasses, including Poa pratensis and Dactylis glomerata. The trees are oak (Quercus garryana). Exotic plant species benefit from fire suppression in these remnant ecosystems, which are rich in native species but also heavily invaded by exotics. The invasives appear to have reduced the abundance of native species in the remnants rather than displaced them, although this is still uncertain since habitat loss and fire suppression may also play roles in the impacts of the invasives. Although few native species have gone extinct, many are low in abundance. This photograph originally appeared on the cover of Ecology (86:1) in January of 2005.

This photograph can be used in discussions about the impacts of non-native species on ecological communities. As MacDougall and Turkington (2005) describe in their paper, the oak-savannah remnant depicted is an example of an ecosystem that has been invaded by many plant species and has maintained a high native species richness. The photograph can be used to demonstrate that the impact of invasive species on native communities can be complex and may be influenced by other factors. In this example, the factors are loss of the surrounding habitat (which has left remnants) and a long-term suppression of fire.